NC: Behavior Change Strategies (2007-2008)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • To compare two different extended treat interventions (relapse prevention therapy and problem solving) with standard behavior therapy
  • To determine whether there was a relative advantage of intensive didactic training in a comprehensive range of relapse prevention skills, compared with continued professional assistance in the form of therapist-led group problem-solving.
Inclusion Criteria:
  • Age: 21 to 60 years
  • BMI: 27 to 40
  • Good health
  • Physician's approval to participate in a diet and exercise weight-loss intervention.
Exclusion Criteria:

None specified.

Description of Study Protocol:
  • Recruitment: Participants recruited from newspaper advertisements and screened for eligibility.
  • Design: Randomized controlled trial.


  • All participants received the same initial cognitve-behavioral weight-loss intervention
    • Weekly two-hour group sessions with 11 to 14 members per group, for 20 weeks
    • Three groups:
      • Behavior Therapy (BT): Two groups
      • Relapse Prevention Therapy (RPT): Three groups
      • Problem-Solving Therapy (PST): Three groups.
    • Standard behavioral weight-management techniques taught in a didactic fasion: Self-monitoring, goal-setting, stimuls control, etc.
    • Instructed to follow 1,200kcal (1,200 per day for women), low-fat diet (25% of total kcal per day)
    • Home-based walking program of 30 minutes per day, five days per week
    • Conducted by pairs of clinical psychology graduate students, who adhered to a written protocol.
  • During year after initial treatment
    • Behavior Therapy
    • Relapse Prevention Therapy
    • Problem-Solving Therapy.

Statistical Analysis

  • Analysis of variance (ANOVA) for comparisons of groups
  • Multi-variate ANOVA (MANOVA) for comparisons of multiple variable between groups
  • Chi-square.
Data Collection Summary:

Timing of Measurements

  • Weight, eating and exercise diaries: Weekly for 20 weeks
  • BT: Weight; six and 12 months
  • RPT and PST: Weight, eating and exercise diaries; bi-weekly for one year.

Dependent Variables

  • Body weight: Scale (type and calibration not specified)
  • Adherence: Self-reported for nine behavioral weight-management strategies (Likert scale; 1=non-adherence and 7=full adherence).

Independent Variables


Description of Actual Data Sample:

Initial N

103 (gender not specified).

Attrition (Final N)

  • Completion of initial behavioral treatment
    • N=88; 80 females and eight males, 85%
    • 80 females included in analysis, eight males excluded because they were unequally distributed between groups.
  • Completion of extended therapy (dropouts were those who withdrew voluntarily or attended fewer than two sessions during Months 12 to 17)
    • RPT: 29%
    • PST: 34%.
  • Final assessment (weight)
    • BT: 83%
    • RPT: 71%
    • PST: 66%.


Final sample: Mean (SD)

  • BT (N=18): 45.23 (10.08) years
  • RPT (N=28): 49.17 (7.21) years
  • PST (N=34): 45.36 (9.33) years.


Not specified.

Other Relevant Demographics


  • BT: 13.13 (1.93) years
  • RPT: 14.00 (1.63) years
  • PST: 14.50 (2.06) years.


  • Height (m) 
    • BT: 1.62 (0.06)
    • RPT: 1.66 (0.06)
    • PST: 1.65 (0.06).
  • Weight (kg)
    • BT: 94.67 (11.35)
    • RPT: 96.95 (13.69)
    • PST: 97.96 (16.01).
  • Body mass index (BMI; kg/m2)
    • BT: 36.37 (4.70)
    • RPT: 35.00 (3.96)
    • PST: 36.10 (4.93).


United States.

Summary of Results:
  • Completers (N=58) vs. non-completers (i.e., dropped out or did not complete final assessment; N=22)
  • Attendance during initial treatment was equivalent
    • Completers: 86%
    • Non-completers: 93%
    • P=0.502.
  • Attendance during extended treatment was poorer for non-completers
    • Completers: 73%
    • Non-completers: 33%
    • P=0.0001.
  • Non-completers had higher initial body weights than completers: 103.2kg vs. 94.4kg; P=0.012
  • Non-completers had non-significatly smaller reductions in percentage of body weight during initial treatment than completers: 10% vs. 8%; P=0.163.

Mean Net Weight (kg) Changes [Mean (SD)] by Conditions Over Time for Completers

Time Period BT (N=15) RPT (N=20) PST (N=23)
Baseline to Month 5
-9.54 (4.94)
-8.41 (4.55)
-9.28 (5.21)
Month 5 to Month 11
2.92 (4.76)
-0.97 (3.89)
-2.05 (3.75)
Month 11 to Month 17
2.47 (3.91)
3.53 (2.96)
0.54 (3.14
Baseline to Month 17
-4.14 (4.86)
-5.85 (6.39)
-10.82 (8.65)

Classification of Participants According to Categories of Change in Body Weight (Percentage) From Baseline to Final Follow-Up

Category of Change BT RPT PST



% N %
Lost 10.0% or greater
Lost 5.0% to 9.9%
Lost 0.0% to 4.9%
Gained weight 


  • A larger percentage of PST participants achieved a clinically significant loss of more than 10% body weight than did BT participants (P=0.025)
  • Differences between the RPT and BT and between PST and RPT were not significant.

Mean (SD) Adherence Scores for Completers by Condition at Months Five, 11 and 17

Assessment Point BT (N=15) RPT (N=20) PST (N=23)
Month 5
53.8 (7.61)
48.7 (4.81)
52.48 (8.01)
Month 11
36.20 (13.91)
42.25 (11.41)
45.78 (9.53)
Month 17
29.07 (10.14)
34.00 (13.39)
38.74 (10.35)
  • PST group demonstrated significantly better adherence to behavioral weight management strategies than the BT group from Months Five to 11 (P=0.043) and from Months 11 to 17 (P=0.041).

Other Findings

  • The effect of treatment condition on weight loss was significant (P=0.01)
  • When analyzed with adherence entered, the results showed a significant effect for conditions (P=0.059). Amount of variance accoudnted for by adherence: R2=0.72.
Author Conclusion:
  • An extended treatment intervention based on a problem-solving model of obesity management demonstrated significantly better weight reduction and long-term maintenance of lost weight than standard BT
  • Extended professional contact alone may not be sufficient to improve long-term weight management.
Funding Source:
Government: Dept. of Veterans Affairs
Reviewer Comments:
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? ???
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) ???
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? N/A
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes